My dissertation titled “Words that Matter: Three Essays on Multilateral Opposition to War” advances our understanding of how the United Nations Security Council (UNSC) constrains state behavior through the use of verbal condemnation. The UNSC has an array of tools to manage violent conflicts, including condemnations, economic sanctions, and military actions. Existing scholarship largely discounts verbal condemnations as ineffective because they are not backed up by coercive actions that impose tangible costs. Empirical patterns and anecdotal illustrations, however, suggest contrary findings – that verbal condemnations can constrain state behavior under certain conditions. I address this gap by examining how variation across UNSC condemnations impacts the crisis-actors’ decision to escalate. I argue that variation in legal invocation and rhetorical severity sends important signals to the targeted state that can change the expected costs of war and, ultimately, prevent escalation. I further examine the determinants of rhetorical variation across UNSC condemnations through the lens of power-sharing and power-politics within the UN. I find that the permanent members influence the contents of the resolution, but the Council President shapes the UN’s agenda. My theoretical expectations and findings are validated by an empirical analysis of international crisis-actors from 1946 to 2017 with the original coding of legality and severity in the UNSC resolutions. This dissertation project improves our understanding of the UN’s role in conflict management, especially through condemnations. The findings suggest that rhetorical tools can be just as effective, and that the UN’s multilateral efforts can mitigate interstate conflicts in world politics by invoking international law and designing impactful messages.